Self-pumping hydropneumatic spring strut

Abstract

A self-pumping hydropneumatic spring strut is provided to have internal level control. The spring strut has an outer tube having one end sealed by a piston rod guide, a working cylinder received inside the outer tube, and a hollow piston rod extending into the working cylinder through the piston rod guide. The piston rod carries a piston, which is operable to travel axially inside the working cylinder in a sealing manner and separates the working cylinder into first and second working spaces. The first working space is under a high-pressure from a high-pressure chamber and acting as a spring and the second working space is located on a piston rod-side. The spring strut also has a pump rod received inside the hollow piston rod. The pump rod and the hollow piston rod form a piston pump, which, in response to sprung movements acted thereonto, conveys a damping media from a low-pressure chamber into the first working space connected to the high-pressure chamber. The high-pressure chamber and the low-pressure chamber are each connected to the atmosphere by a filling connection formed in the piston rod guide and a check valve operable to selectively communicate the high-pressure or the low-pressure chamber to the atmosphere.